Process for refining hydrocarbon oils by means of esters



meme Jan. 24, less PROCESS FOR REFINING HYDROGARBON OILS BY MEANS OF ESTERS Ernest Teri-es, New York, and Erich Saegebarth,

Long Island City, N. Y., and Josef Moos, Berlin-Mariendorf, Germany, assignors, by mesne assignments, to Edeleanu Gesellschaftm. b. 11., Berlin, Germany, a corporation of Germany i No Drawing. Application March 22,1935, Serial No. 12,526

28 Claims. (Cl. 196-13) This invention relates to the refining of hydrocarbon oils, such as mineral oils, and oils made from coal tar and bituminous coal tar.

In particular this invention relates to refining hydrocarbon oils by means of selective solvents. Selective solvents have been used heretofore for this purpose and their action consists in dissolving the undesirable fractions which contain mainly aromatic, hydroaromatic and unsaturated hy- Emample 2 A sample of the same Mid-Continent distillate as described above wasextracted two times with 100 vol. each 'of tributyrin (glyceryl-tri-butyrate) at 75 F. The rafllnate and extract layers were separate from each other after each treating step and, after removal of the solvent, 63.3 wt. of raffinate was obtained having the following properties:

drocarbons, so that the remaining non-dissolved fraction or raflinate shows greatly improved spec- "A. P. I. gravity 26.8 iflcations. Saybplt viscosity at 100 F 781.0 I We have now found that mono-, diand'tri Saybolt viscosity at 210 F 77.0 acetin, mono-, diand tri-propionin, and mono-, Viscosity index 96.4

diand tri-butyrin, are very suitable for. refining hydrocarbon oils, such as mineral oils, coal tar or bituminous coal tar oils or fractions thereof. The acetins, propionins and butyrins are mentioned only as examples of theglycerol derivatives, and it is understood that theglycerol derivatives of the higher fatty acids are likewise included.

In carrying out our invention we employ either a 'countercurrent tower mixer or an equipment consisting of mixing and settling stages, in order to contact the hydrocarbon oils to be extracted with our solvents. The products, that is the hydrocarbon oils, and one or more of our solvents are introduced into the treating system in such a way that the well known c'ountercurrent wash ing effect is obtained. A

As an illustration of the eflect of our solvents we mention the following examples. Itis to be understood that these examples serve as an in-' dicationonly and do not cover the entire scope of our invention. Example 1 A Mid-Continent distillate having specifications as shown below was extracted three times with 100 vol. each of tripropionin (glyceryltri-propionate) at 210 F. The extract layers were removed from the railinate layer after each Instead of using one of our above cited selective solvents, we may also employ a mixture of two or more of them for extraction.

In some cases we prefer to employ our solvents in the presence of auxiliary solvents. .The auxiliary solvents we divide into three classes.

Class 1, of the auxiliary solvents is characterized by being entirely miscible in any proportion with our selective solvents and also with the hy- I drocarbon oils to be treated. Representatives of this class are the aromatics, hydroaromatics, the non-selective aliphatic and aromatic halogen derivatives, the non-selective ketones ethers, esters and others. On account of the miscibility in our selective solvents and in the hydrocarbon oils, this class of auxiliary solvents serves to increase the solvent power of our selective solvents.

In other cases we prefer to decrease the solvent power of our selective solvents. This is, for example, feasible in treating naphthene base oils which contain a large percentage of the undesirable fraction or extract. For this purpose we 7 employ Class 2 of auxiliary solvents which are identified by being entirely miscible with our selective solvents but not or only a little miscible with the hydrocarbon oils to be extracted. Representatives of this class are alcohols, organic acids or water.

In still other cases, for example, in treating residual oils we employ our selective solvents in presence of Class 3 of the auxiliary solvents to Ummmd Ramnate tane, etc. or mixtures thereof. This Class 3 of 50 Stock selective solvents 1S identified by being entirely f miscible only with the hydrocarbon oils but not a .e.'r 23.0 28.0 1 with our selective solvents. Representatives of 523. 5;; 5:2 3%; Class 3 of auxiliary solvents serve to improve the Viscdsityifl -mi a 73.7 109 selectivity of our selective solvents.

A further object of our invention is, whenever we treat waxy stocks, to remove the solid paraifine-like hydrocarbons either independently from the extraction stepor combined with it in any desired order. We may, for example, first dewax the stock to be refined and then follow with extraction, or we may start our process with extractionby means of our selective solvents, mixtures thereof or in mixture with one or more representatives of the three classes of auxiliary solvents mentioned above, and may then dewax the solvent treated rafiinate. In the latter case we do not charge the waxy ratflnate solution, that is the waxy raffinate saturated with the auxiliary solvents and/or the selective solvents, to the solvent recovery system but prepare it further for the dewaxing step, as will now be described.

Our selective solvents, when blended in proper proportion with one or more auxiliary solvents of the Classes 1 and 3, represent very suitable diluents for the removal of solid parafiine-like hydrocarbons. In order to carry out the dewaxing either of the original stock or of the waxy solvent rafflnate, we add sumcient quantities of one or more of our selective solvents and one or more of the two classes of auxiliary solvents in order to reduce the viscosity of the solution and make it suitable for the separation of the wax, which may be carried out either by decanting, filtering or centrifuging.

In preparing the solution of hydrocarbons in the dewaxing diluent, we take care that a proper mixture is used so as to'prevent separation into two liquid phases at the temperature at which the dewaxing is carried out.

The slack wax which is obtained in the dewaxing process may be further refined to petrolatum, if this is desired. For this purpose we extract the slack wax with a suitable blend of the selective solvents with the auxiliary solvents of Classes 1-3, in order to effect the removal of all liquid hydrocarbons which might be present in the slack wax.

The solvents which were used in the extraction process and/or in the dewaxing process are usually recovered by distillation. If the extraction is followed by dewaxing, a certain amount of extraction solvent is carried over into the dewaxing unit. This solvent is segregated by a fractional distillation and is recycled into the extraction part of the plant.

Instead of removing by distillation the solvents from the rafiinate or extract layer or from the dewaxed oil solution, we may also employ one or more other solvents which dissolve our selective and auxiliary solvents but which do not dissolve the hydrocarbon oils.

Having thus described our, invention, what we claim is:

1. A process for refining hydrocarbon oils characterized by extracting the oil with a selective solvent comprising a glyceryl ester of a higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical, at a temperature at which the oil and extract form separate layers, separating the layers and recovering the solvent therefrom.

2. A process for refining hydrocarbon oils by solvent extraction as described in claim 1 in which the selective solvent comprises a glyceryl ester of a higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical and an auxiliary solvent which is miscible in any proportion therewith and with the oil.

3. A process for refining hydrocarbon oils by solvent extraction as described in claim 1 in which the selective solvent comprises a glyceryl ester of a higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical and an auxiliary solvent which is miscible in any proportion therewith and with the oil,'said auxiliary solvent being selected from the group of organic compounds consisting of aromatics, hydroaromatics, and the non-selective aromatic halogen derivatives.

4. A process for refining hydrocarbon oils by solvent extraction as described in claim 1 in which the selective solvent comprises a glyceryl ester of a higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical and an auxiliary solvent which is miscible in any proportion therewith but which is not wholly miscible with the oil.

5. A process for refining hydrocarbon oils by solvent extraction as described in claim 1 in which the selective solvent comprisesa glyceryl ester of a. higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical and an auxiliary solvent which is miscible in any proportion therewith but which is not wholly miscible with the oil, said auxiliary solvent being selected from the group consisting of alcohols.

6. A process for refining hydrocarbon oils by solvent extraction as described in claim 1 in which the selective solvent comprises a glyceryl ester of a higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical and an auxiliary solvent which is entirely miscible in any proportion with the oil but is not entirely miscible with said glyceryl ester.

'7. A process for refining hydrocarbon oils by solvent extraction as described in claim 1 in which the selective solvent comprises a glyceryl ester of a higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical and an auxiliary solvent which is miscible in any proportion with the oil but is not entirely miscible with said glyceryl ester, said auxiliary solvent being selected from the low boiling members of the class of paraifinic hydrocarbons.

8. A process for refining hydrocarbon oils characteriped by extracting the oil with a selective solvent comprising a glyceryl ester of a higher homologue of acetic acid containing at least two car- .1 bonatoms in the alkyl radical, at a temperature atgw hich the oil and extract form separate layers, separating the layers, dissolving the raifinate without removing the solvent in an added amount carbon atoms in the alkyl radical, at a tempei'ature at which the oil and extract form separate layers, separating the layers, dissolving the raffinate; without removing the selective solvent, in an added amount of selective solvent containing an auxiliary solvent miscible with the oil in proportions to prevent separation into two liquid layers, cooling the solution to a temperature at which the wax solidifies, separating the wax from i the oil, recovering the solvents from the dewaxed oil and wax, respectively, segregating the selective solvent used in the extraction step and contained A 2,146,186 in the dewaxed ramnate solution, and recycling said segregated selective solvent to the extraction step for reuse.

10. A process for dewaxing hydrocarbon oil characterized by dissolving the oil at a suitable temperature in a blend containing a selective solvent and an auxiliary solvent, said selective solvent comprising a glyceryl ester of a higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical and said aux iliary solvent being an organic compound which is miscible in any proportion with the oil, the proportions of said solvents being such as to prevent the separation oi" the oil-solvent mixture into liquid phases, cooling the mixture to a tempera-.-

ture at which the wax solidifies and separating the solid wax from the liquid, and recovering the solvents from the separated wax and oil.

11. A process for dewaxing hydrocarbon oils characterizedby dissolving the oil at a suitable temperature in a blend containing a selective solvent and an auxiliary solvent, said selective solvent comprising a glyceryl ester cl 9. higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical and said auxiliary solvent being an organic compound which is miscible in any proportions with the oil, the proportions of said solvents being such as to prevent the separation of the oil-solvent mixture into liquid phases, cooling the mixture to a temperature at which the wax solidifies and separating the solid wax from the liquid, extracting said separated liquid with a blend of thesame solvents containing the selective solvent in greater proportion, and recovering the solvents from the separated wax and oil.

12. A process or refining hydrocarbon oils as specified in claim 1 in which the selective solvent is a glyceryl ester of propionic acid.

13. A proces of refining hydrocarbon oils as specified in claim 1 in which the selective solvent is a glyceryl ester of butyric acid.

14. A process 01' refining hydrocarbon oils asvv specified in claim 1 in which the selective solvent is tri-propionin.

15. A process of refining hydrocarbon oils as specified in claim 1 in which the selective solvent is tri-butyrin.

16. A process 01' refining hydrocarbon oils as is a glyceryl ester of propionic acid.

17. A process of refining hydrocarbon oils as specified in claim 8 in which the selective solvent is a glyceryl ester of butyric acid.

specified in claim 8 in which the selective solvent 18. A process of refining hydrocarbon oils as specified in claim-8 in which the selective solvent is tri-propionin. v

19. A process of refining hydrocarbon oils as specified in claim 8 in which the selective solvent is tri-butyrin.

20. A process of refining hydrocarbon oils as specified in claim 10 in which the selective solvent is a glyceryl ester of propionic acid.

21. A process of refining hydrocarbon oils as specified in claim 10 in which the selective solvent is a glyceryl ester of butyric acid.

22. A process of refining hydrocarbon oils as specified in claim 10 in which the selective solvent is tri-propionin.

23. A process of refining hydrocarbon oils as specified in claim 10 in which the selective solvent is tri-butyrin.

24. A process of refining hydrocarbon oils as specified in claim 11 in which the selective solvent is a glyceryl ester of propionic acid.

25. Aprocess of refining hydrocarbon oils a specified in claim 11 in which the selective solvent is a glyceryl ester of butyric acid.

-26. A process of refining hydrocarbon oils as specified inclaim 11 in which the selective solventis tri-propionin.

2'7. A process of refining hydrocarbon oils as specified in claim 11 in which the selective solvent is trl-butyrin.

28. A process for refining hydrocarbon oils by solvent extraction as described in claim- 1 in which the selective solvent comprises a glyceryl ester of a higher homologue of acetic acid containing at least two carbon atoms in the alkyl radical and an auxiliary solvent which is miscible in any proportion therewith but which is not wholly miscible with the 011, said auxiliary sol- 

